1. Field of the Invention
The present invention relates to an apparatus for melting and treating metal wastes, such as radioactive metal wastes from nuclear power plants and metal scrap from polluted equipment, and to a melting and treating method using said apparatus. More particularly, it relates to a melting and treating apparatus and method capable of safely and efficiently reducing the volume of polluted metal wastes in a closed system.
2. Description of the Prior Art
With the advancement of atomic energy application technology, the amount of radioactive metal wastes is increasing as is metal scrap from polluted equipment. At present, these kinds of wastes are sealed in drum cans, containers and the like and stored in the site, but the limited storage capacity calls for a volume reduction.
So far as combustible radioactive wastes are concerned, such volume reduction treating technique based on incineration has been established, and incinerators for radioactive combustible wastes have been installed or are scheduled to be installed in atomic power plants and atomic energy research institutes. As for incombustible materials, such as radioactive metal wastes, a volume reduction method comprising fragmentization and compression is being practiced but can hardly be said to have achieved sufficient volume reduction.
As for volume reduction treating methods handling various metal wastes, melting and treating methods are known. With these methods, it is possible to achieve high-density volume reduction of metal wastes, and the very high mechanical strength of the cooled solidified mass provides certain merits including easy handling and rare occurrence of re-diffusion (efflux, disintegration and dispersion, etc. of harmful metals). Such melting and treating methods include an electroslag melting method, a high frequency melting method, a plasma arc melting method, a nonconsumable electrode arc melting method induction slag melting method, etc.
Therefore, application of said melting and treating methods to radioactive metal wastes may be contemplated, but to put such methods in practical use it is necessary to ensure prevention of radioactive pollution during the melting and treating operation.